Electric plug



June 17, 1947. J N Y Y 2,422,393

' ELECTRIC PLUG Filed NOV. 17, 1945 Patented June 17, i 1947 ELECTRIC PLUG Frank D. Bryant, Wetlierslield, Conn., assignor to Royal Electric Company, Inc., Pawtucket, R. 1., a corporation of Rhode Island I I ,Application November 17, 1945, Serial No. 629,280

This invention relates to plugs commonly used to connect the conductors of electric lamps and other electric appliances to supply outlets or couplings, and the principal purpose of the invention is to provide improved means for electrically con- I necting the conductors to the ends of the blades.

and for securing the blades and conductors within the housing.

The most common electric plug heretofore used is the familiar type in which the blades are secured within a two-part housing by screws, and the conductors are connected to the blades by additional screws; other plugs have the conductors soldered or clamped to the blades. In some cases, one piece housings of resilient material have been employed, in which saw tooth blades are pushed into the housing and against the conductors and held in engagement by impingement -of the blade teeth in the recesses of the housing. All of these expedients require the use of tools in assembling the plugs, or the use of a special housing material; and the connections frequently loosen, thereby impairing the efliciency of the p g. a

The principal advantages of the present invention are that any non-frangible material may be used for the housing material; positive retention of the blades within the housing is afforded; a

good and durable electrical contact between the electrical conductor and the blades is provided; economies of manufacture are effected due to the small number of parts'required; and firm anchorage of the cord to the housing, which is so important in resisting separation of the parts when the plug is pulled from the supply outlet, is ensured.

In the. drawings, i

Fig. 1 is an elevation of the assembled plug with internal parts shown in dotted lines;

a Fig. 2 is a sectional view of the one-piece hous-' ing, with the conductor wires and blades. in anchored position;

Fig. 3 is a similar view of the housing, with the conductors and blades removed;

Fig. 4 is,.a longitudinal section taken on line -4-4 of Fig. 1; and

Fig. 5 is a transverse section taken on line 5-5 of Fig. 1.

The housing is preferablymolded in one piece. of thermo-setting, thermoplastic, or other suitable material, and contains a plurality of receases or openings intended to receive a conductor 12 having a pair of insulated wires l4, and the ends of blades l8, in such a manner as to provide firm electrical contact between t e l s 6 Claims. (Cl. 173-361) 5 wedge or partition 20, which 30 to press the fingers together.

and the bare ends of the wires and also to clamp the insulation of the wires within the housing. Recess I8 is shaped to accommodate the conductor l2, and is directed toward an interior is disposed between blade recesses or slots 22. The purpose of the wedge 20,-which is preferably integral with housing I0, is to direct the respective wires into lateral passages 24 connecting the cable recess I8 with in the blade slots 22. Each of the blades I6 is fabricated from brass sheeting or any other electrical conducting material, preferably doubled upon itself in such a way as to provide a straight, twoply. outer prong for insertion into a conventional electrical supply outlet, and two spaced, inner arms, 28 and 28 which are recessed in housing It and disposed in the complemental blade slot.

The inner arm 28 isslotted as shown at 38 (Fig. 4) to provide spring fingers 3|, and the slot 38 has a circular mouth at the forked tip of the arm which exerts a clamping action on the wire insulation 32 when the insulated wire is engaged by saidforked tip and pressed against a shoulder 34 of the housing. This clamping action is achieved by making the circular mouth of slot smaller than the diameter of the insulated wire,

to produce a spring grip between the tips of the resilient fingers 3|; and by the decreasing taper. of blade recess 22, as shown in Fig. 4, which tends Although the clamping grip afforded by either of these two structural features would be suillcient both are recommended as a preferred arrangement for optimum security. 1 J

Another important purpose of the decreasing taper of bayonet recess 22 is to form interior shoulders 36, which in conjunction with hooks 38 formed on the flexible fingers of the arm 26, provide a positive locking action between the 40 blade arm 28 and the housing l8, when the hooks are snapped over'the shoulders 36 upon insertion of the blade. Besides retaining blade [Bin housing I0, this locking action ensures a secure electrical contact between the bare end of conductor wire l4 and the tip of the blade arm 28 which is of such length that a longitudinal, compressing or clamping action is exerted on wire l4, thereby bending the wire over the arm tip and forcing it against the bottom of recess 22, behind shoulder 34, when the blade is locked in the housing.

The plug is assembled by inserting theconductor l2 in recess l8until the insulated wires H are spread by the wedge 28 to occupy the respective passages 24, and then pressing the blade a ms 36, 28 into the slots 22 until the locking ing a conductor a. pair of blade-receivingslots at 'means' within the 'hooks 38.snap over the housing shoulders 38,

thereby permanently clamping the parts together with firm mechanical and electrical engagement between the conductors and the blades, and those parts and the one-piece housing in which they are contained.

I claim: v

1. An electric plug comprising a housing havrecess and a pair of blade-receivflexible, housing ing slots, a, conductor having a-pair of entering said recess. the

ing a conductor recess and a pair of blade-receiv-v ing slots, a conductor having a pair of flexible, insulated wiree entering said recess, the housing havinglateral passages receiving the respective wires an leading to the respective slots, a pair. of blades for attaching the plug to an outlet, each said arms in clamping position.

spring fingers engaging the insulated wire and passages receiving the respective 3. An electric plug comprising a housing hav ing a. conductor recess and a pair of blade-receiving slots, a conductor having a pair of flexible, insulated wires entering said recess, the housing having lateral passages receiving the respective wires and leading'to the respective slots, a wedge at the'bottom of said recess for directing the wires into the respective passages upon insertion thereof into the-housing, the sides of the wedge forming the inner walls of said slots, a pair of blades for attaching the plug to an outlet, each blade having a pair of laterally spaced arms reand means securing the blades within the nous ing an locking said arms in clamping position.

4. An electric plug comprising a one-piece housing having a. conductor recess .at one end, its other'end, and lateral passages between said recess and the respective slots, a. conductor received in said rethe wires extending into the bottom plug ifor directing the wires of said slots,

i in clamping position.

into said passages when inserted endwise into said recess, a pair of attaching the plug to blades having prongs for an outlet, each blade having a pair of laterally spaced, resilient arm's reof the outer ceived in one of 'saldslots, thetip end and clamping it against arm engaging a wire th housing, and the inner am having a pair of 5. An electric plug comprising a one-piece housing having a conductor a pair of blade-receiving slots at its other end, an lateral passages between in the respective passages with the of the wires extending into the bottom of said slots, a partition integral with the housing and 6. An electric plug. comprising housing having a. conductor recess at one end, a pair of blade-receiving slots at its other end, and lateral passages between said recess and the bared ends a one-piece respective slots, a conductor received in said re- 1,

having a pair of RANK D. BRYANT. 

